connecting rough-in 3rd level shower, sink and toilet vent stack

Hello,
I am completing the 3rd level of my home and need to know if the roughed in vent stacks extending approx. 18" through floor need to be connected and extended through the roof. There are 2 stacks, one on the wall with the toilet and sink and the other on the shower wall. They are both capped off. How do I proceed.